You weren't meant to see this, he thought that you were still buying supplies with Bepo. Seeing you in the doorway with a look of shock is very understandable, he just pretty much killed someone that was being rude to you while you were shopping with Bepo.

"Baby I—"

He didn't know what to say or how to defend himself on his actions, he knew it was wrong, he just didn't care. It was all for you.

"I couldn't let him treat you like that, baby.. Needed to do something."